Impact of Orbit Prediction Accuracy on Low Earth Remote Sensing Flight Dynamics Operations

Abstract

This paper addresses the problem of orbit prediction and its impact on flight dynamics operations. In general, certain “knowledge” of the satellite’s orbit is necessary to design and implement a ground-in-the-loop orbit control system. The operational constraints imposed by Low Earth Orbit (LEO) satellites and the stringent orbit control requirements driven by the use synthetic-aperture-radars (SAR) on board the satellites, give great importance to the orbit calculation chain. After a brief discussion on how the orbit determination using on-board Global Positioning System (GPS) measurements is performed and then predicted ahead by precise force modelling, the paper focuses on the prediction accuracy evaluation. Appropriate on-going satellite missions are selected as test-beds, accurate GPS based Rapid Science Orbits (RSO) are used as references to evaluate the prediction errors. Finally the results are applied to the German TerraSARX (TSX) flight dynamics system design. If the long-term prediction accuracy (days) is shown to dictate the nominal maneuver planning and execution concept, the short-term prediction errors (hours) are expected to influence the orbit control performances and to pose critical limits to the minimum achievable interferometric baseline (IB) using a ground-based orbit control.